Field of the Invention
The present invention relates to a lithography apparatus, a power supplying method, and an article manufacturing method.
Description of the Related Art
A lithography apparatus transfers a desired pattern onto, for example, a substrate in lithography steps included in manufacturing steps for articles such as a semiconductor device, a liquid crystal display device and the like. An exposure apparatus, which is an example of the lithography apparatus, transfers (exposes) a pattern formed in advance on an original (a reticle, a mask or the like) onto the substrate (a wafer, a glass plate or the like), on which photosensitive material has been applied, via a projection optical system. A wafer stage, a reticle stage, a masking blade and their active counters are driven in synchronization to each other during a scan exposure with a step-and-scan type semiconductor exposure apparatus. Similarly, a plate stage and a mask stage are driven in synchronization to each other during a scan exposure with a step-and-scan type liquid crystal exposure apparatus.
In the exposure apparatuses described above, an improvement of throughput is required from the viewpoint of productivity. As an important element for high throughput, there is a high speed driving of a stage device which hold the substrate, the original or the like and are movable as described above. In general, a rigid material is used for a structure body of the stage device in order to prevent deformation during a high-speed drive, so that stage weight tends to increase. Particularly in the liquid crystal exposure apparatus, a stage size also increases according to the requirement for increasing a size of the glass plate, so that stage weight tends to increase. Meanwhile, a highly-efficient linear motor is generally used as an actuator of the stage device. Moreover, the stage device having a high-acceleration and high-weight often comprises the linear motors positioned in parallel in order to obtain high thrust.
However, in a case where the stage device is driven at high speed employing the linear motor, a driver is required to supply a large amount of power to the linear motor, especially during acceleration upon the deceleration. Firstly, the driver needs to obtain power to be consumed from any of power sources in an acceleration period of the stage device. Meanwhile, little power is consumed in a constant speed period since little thrust is required. Then, a regenerative electric power returns to the power source since a counter electromotive force of the linear motor is generated in a deceleration period. In the above structure of the device, a peak power is generated upon the acceleration and the peak power returns upon deceleration. Accordingly, the peak power in the lithography apparatus such as the exposure apparatus increases and the power consumption increases according to high throughput, so that enlargement of a size of the power source and extension of equipment may occur. For example, in order to suppress an increase of voltage in the power source caused by returning the regenerative electric power upon deceleration, employing a high capacity capacitor as the power source for the driver to avoid increasing the size of the power source can be considered. An exposure apparatus which employs a high capacity capacitor for suppressing the increase of the size of the power source and compensates power source amount upon the acceleration requiring a considerable amount of power is disclosed in Japanese Patent Laid-Open No. 2002-369579.
However, particularly in a step-and-scan type exposure apparatus, timings of acceleration requiring a considerable amount of power overlap since the substrate stage, the original stage, or other driving units are driven in synchronization. Accordingly, the peak power of the whole device is likely to increase considerably compared to the other types of the exposure apparatuses, and further improvement is desired. In contrast, while reconsidering methods of driving in synchronization may be reviewed, a decrease of throughput may be caused depending on exposure conditions.